feat: enhance interactive prompts with variable descriptions and contextual icons (#118)

## Overview
Improves the interactive variable prompting experience by displaying
variable descriptions, contextual icons, and bold variable names for
better user guidance.

## Changes

### Core Features
- **Variable Descriptions**: Display `description` field (or `help` as
fallback) when prompting users in interactive mode
- **Contextual Icons**: Automatically select appropriate emojis based on
variable names and types:
  - 🚀 Project/app names
  - 🌍 Environment/deployment variables
  - 🔌 Ports/network settings
  - 🗄️ Database configurations
  - ⚡ Boolean/toggle options
  - 🔐 Authentication/secrets
  - 🏷️ Versions/tags
  - 📁 Paths/directories
  - 🔧 General variables (default)
- **Bold Variable Names**: Improve readability with ANSI bold formatting
in terminal
- **Smart Formatting**: Conditional display based on description
presence (compact for no description, full for descriptions)

### Implementation
- Added `_get_variable_icon()` method in `TemplateRenderer` for icon
selection logic
- Enhanced `prompt_for_missing_vars()` to handle descriptions and
formatting
- Proper enum handling with options display

### Documentation
- Updated `docs/template-variables.md` with visual examples
- Documented contextual icon selection
- Noted `description` and `help` field support

### Testing
- Comprehensive test coverage for new formatting and icon logic
- Tests for enum and non-enum variable prompts

### Additional
- Updated WARP.md with GitHub MCP issue management guidelines

Closes #116

Author: httpdss